Well the 185 aside (I don't have it) My results and tweaks so far are thus.
I changed the line RejectThreshold to the figure below, I have a 1GB card, the commented out number is for a half GB card I tried it as apparently this should be as low as possible, I don't know why, but I found the terrain textures loaded faster with the high number and no loss of FPS, the commented out numbers are for reference back and forth during the test:
RejectThreshold=1048756 //524288 //1048756
Another tweak that had a major impact was the Lod radius, I changed this from 4.5 (default) to 6 (I tried 5.5 and 6.5) 6 was the best setting. What this setting does is determine how far out from your plane the high res texture will be loaded, it is therefore a very system specific setting and will require some experimenting, but having a higher number means that the lower res textures are now a good deal further out and so I don't see as much very blurry terrain as before and the whole thing looks a good deal better. It doesn't seem to load up any slower either, but at 6.5 it did start having a job to keep up and thus the effect was spoiled, so 6 was the highest I could get to.
I did not disable the external FPS limiter (this is really a pretty important part of getting a smooth look, reducing the stutters etc) and also to allow for better terrain tex loading.
So, now I can see decent res textures out to a good distance (about a mile) at that range the next lower res textures look very good and so on, it keeps up pretty well at around the 170 kias but struggles a little over that, but not so it is a constant struggle, just doesn't always catch up in time with every tile etc. But overall the performance and appearance have improved dramatically and I am happy with it now. My external FPS limiter is set to 20FPS, internal to no limit.